[Visualization of the intra-stent lumen in the coronary arteries and detection of restenoses with 64-slices tomography scanners with cardiac synchronization: first experience].
OBJECTIVE
to assess the value of the new high spatial resolution 64-slice CT (0.4 mm collimation) technology for non-invasive visualization of coronary artery stent lumen and the characterization of significant in-stent restenosis.


METHODS
a total of 100 stents were visualized in 50 consecutive patients. All CT examinations were performed with a 64-slice CT (sensation 64; Siemens), with a slice thickness of 0.75 mm at 0.5 mm intervals with retrospective gating. Images were evaluated by two readers and the quality of the in-stent lumen was classified on 5-point scale (1 = not visible; 5 = excellent visibility). Fifty-eight stents in 29 patients were also examined by conventional coronary angiography one week after CT examination. Attenuation values were measured in the vessel upstream from the stent and within the stent, using 1 mm2 regions of interest. The intra stent attenuation ratio (ISAR) was calculated as vessel enhancement/intra stent hypodense area. Interobserver agreement was evaluated by kappa statistics,


RESULTS
the interobserver agreement was k= 0.82. The in-stent lumen was visible (score > or =3) in 88 stents (88%), with good visibility (> or = 4) in 54% of stents. Unsatisfactory in-stent lumen visibility was associated with heart rate > 65 beat/min (p < 0.001) and stent size < 3 mm (p < 0.0001). In-stent visibility was also lower in circumflex than other arteries (p= 0.02). Thirteen stenoses or occlusions were detected in 8 patients. In-stent restenosis was associated with hypodense areas within the stent. A ISAR>2 was an accurate criteria (2 false positives, 0 false negative) for detection of significant (> 50%) intra-stent restenosis.


CONCLUSIONS
high resolution 64-slice CT allows reliable in-stent visualization for stents of 3 mm or more in diameter, if heart rate is below 65 bpm. Significant restenosis can be detected with a high sensitivity by determining the ISAR. Arch Mal
Larchez
C
C
Service de radiologie, centre chirurgical Marie-Lannelongue, Le Plessis-Robinson. christophe.larchez@laposte.net
Daoud
B
B
Ghostine
S
S
Caussin
C
C
Lancelin
B
B
Paul
J F
JF
D017023:Coronary Angiography; D023903:Coronary Restenosis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D023921:Coronary Stenosis / Q000000981:diagnostic imaging / Q000601:surgery*; D003331:Coronary Vessels / Q000601:surgery*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012189:Retrospective Studies; D015607:Stents; D014057:Tomography, X-Ray Computed